Rimes considers herself a "bonus mom" to new hubby Eddie Cibrian's two sons -- Mason, 7, and Jake, 4. (Their real mother, Brandi Glanville, sparred with Rimes publicly in the press until recently, when the two called a truce.)

"My first bonus mom day will be spent with Eddie here in Canada!" she wrote on her Twitter page Thursday. The singer-actress began shooting her new film, Reel Love, in Ontario on Monday. When one of her followers pointed out she wasn't actually anyone's mother, she replied: "It's not called stepmom's day lol common sense would explain that!!"